Misfire

[locksmith]

I have a 2004 Ranger Edge 4.0L w/5 spd. auto. Two weeks ago I had the plugs and wires changed after 101,000. It ran fine for a week. It has developed a bad misfire under load. It starts fine and idles fine, but under load it tries to shake itself apart

I replaced all four O2 sensors today, but now it runs worse. Any suggestions would be helpful. It shows no codes and the check engine light has not come on.

 

[Explorin94]

Start with rechecking all the connections. Make sure they are tight and clean. Basically just reverse what you did when you tuned it up.

 

[06RangerXLT]

ok. i had the EXACT same problem, and i fixed it. you have a cracked spark plug. mine wasn't chipped, the porcelain separated from the plug and you could spin it.

Ford put it in, and their "best tech" screwed it up. pull the boot on each, check the porcelain and give it a wiggle, to see if its come loose.


I hated when i had that. could drive along just fine, but as soon as you gave it gas, it felt like the engine was trying to rip itself of the car!

let me know, PM me if you have trouble.

also, check the boots of the wires that go over the plug. mine had a cut in it. they can be easily damaged if not done right.

 

[locksmith]

Thanks for the input. This is very frustrating not being able to solve this. I had two mechanics with a scanner on it yesterday and the only anomoly was the O2 sensors. It does not throw out any codes.